Power Steering & an electrical fault

[Rhythm Addict]

I've got a 308D Sprinter on a P Plate which has started leaking oil and losing assistance from the power steering. From a quick visual inspection the oil is not coming from anywhere near the pump at the top of the engine but might be coming from either the pipework under the engine or near the steering rack itself. Anyone else had this kind of problem and if so how easy/costly was it to get sorted.
In addition on the same vehicle I have the usual soggy brake pedal but if I turn sharp left at low speed there is a loud buzzing noise as if it's triggering the ABS. If I hit the brake pedal whilst it is making the noise the old solid brake pedal is back so they must be linked. What should I be looking for to find out what is causing the triggering of the ABS?